Encoding in the real world

Encoding in the real world

1. Simon & Emmons (1956)

   • During sleep participants hear questions and answers every five minutes. Participants EEGs are recorded throughout the night to monitor their sleep. Subsequently, they are asked the questions they heard overnight.
     • Overall: performance is above chance.
     • Awake but relaxed... 80%. Drowsy...................50%. Drowsy / Light sleep..........5%. Asleep......................No effect.

2. Bruce, Evans, Fenwick & Spencer (1970)

   • Present material to sleeping subjects then awaken them immediately. No evidence for memory.
     • The absence of learning about external events while asleep does not imply that we can't remember internal events such as dreams (Pace-Schott et al, 2003), or that sleep itself might not play an important role in the consolidation of memories (Hahn et al, 2006; Paller & Voss, 2004).

3. Memory during anaesthesia (Levinson, 1965)

   • 10 dental surgery patients in a mock crisis during surgery. 4 patients produced almost verbatim reports of the anaesthetist's comments. 4 produced partial reports and only 2 produced no recall at all under hypnosis.
   • Problems with Levinson
     • - Serious ethical questions. - No control condition. - Suggestibility of hypnosis. - Experimentor bias. - No measure of anaesthesia.
   • However, (1) Anaesthesia may not be total - cocktail issue: [Anaesthetic, Analgesic & Muscle relaxant]. (2) Different tests of memory may reveal different evidence for memory from anaesthesia.

4. Explicit vs. Implicit memory

   • Explicit memory requires conscious recollection of prior experiences
     • Typical Explicit memory tasks. FREE RECALL: Subjects attempt to remember target information without any assistance from the experimentor.
     • CUED RECALL: Subjects attempt to remember the target information in the presence of some specific cue e.g. an associate of the word he or she is trying to remember.
     • RECOGNITION: Subject is presented with a stimulus and must decide whether it is one that he or she was asked to remember.
   • Implicit memory is revealed on tasks that do not require reference to a specific episode.
     • Iselin-Chaves et al, 2005.
       • Depth of anaesthesia carefully measured. Participants listen to 2 lists of 20 words, each presented 25 times. One word presented each 4 seconds. Words are all 6 letters long, and each word shares a stem (first three letters) with at least 4 other french words. e.g. CHA
     • Jacoby (1991) Process Dissociation Procedure
       • Inclusion test: Produce items from any source. Exclusion test: Only produce items that you didn't study previously.
         • Inclusion = R + A (1-R). R = conscious recollection.
         • Exclusion = A(1-R). A is unconscious or Automatic memory.
         • Therefore, R = inclusion - exclusion., and A = Exclusion / (1-R)

5. Weapon focus (Loftus, 1979; Loftus & Messo, 1987)

   • The idea that arousal (during a crime) causes attention focusing such that only 'central information' is attended to. For example, the attacker's knife rather than the face.
   • Experimental demonstrations (e.g. Christianson & Loftus, 1991). Change in eye movements in stressful situations is relatively easy to demonstrate e.g. Chapman & Underwood (1998) though memory changes can be more subtle (Wessel et al, 2000).